Program or method and device for detecting an audio component in ambient noise samples
The amount of data produced in the process of recording even short hearing samples by means of a monitor may be considerably reduced by effecting a normalization to a range of values D and a subsequent nonlinear mapping to a second, preferably smaller range of values W. The result may be stored in an electronic memory. Further preferred measures are the splitting of the hearing samples into e.g. 6 signals each of which contains a respective frequency band of the original signal, and the conversion of the original amplitude values into energy variation values with simultaneous low pass filtering. Preferably, all cited processing steps are performed by a signal processor. A continuous recording time of up to 14 days by a monitor in the form of a wristwatch can thus be attained with state-of-the-art technology.
1. Method for evaluating hearing samples of ambient noise recorded by at least one first device in at least one first location where programs to be monitored are received, the hearing samples being obtained by a method comprising recording samples of an ambient noise using a sound transducer, the sample duration being shorter than the sampling cycle, the method for evaluating hearing samples comprising
recording, by at least one second device in at least one second location where the programs to be monitored are broadcast, a plurality of samples of the programs to be monitored wherein each of the samples of programs to be monitored has a greater duration than a corresponding one of the recorded hearing samples, and
calculating a first correlation for comparing the hearing samples with the program samples in order to find a match, a match occurring if a program sample is considered to be contained in a hearing sample,
each of the hearing samples being taken during a respective first period of time completely included in a respective second period of time during which a corresponding one of the program samples is taken.
2. The method of claim 1 , wherein the method of obtaining the hearing samples further comprises:
normalizing the amplitude of the recorded audio signal within a first predetermined range D; and
mapping the normalized amplitude values of the audio signal onto a second predetermined range of values in the time domain using a non-linear mapping function to obtain an emphasis of selected values ranged within the first or the second predetermined ranges,
and wherein the recordation of the samples of the ambient noise is periodic.
3. The method of claim 1 , wherein said first correlation is a standard correlation according to the formula
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N: number of values of the hearing sample which are used in the correlation,
t: time shift
s i : hearing sample value at the time i,
m i-t : program sample value at the time i−t,
c t : correlation value for the time shift t: −1≦c≦1.
4. The method of claim 1 , wherein the recording of the program samples is started sufficiently before the hearing samples and the program sample recording is sufficiently longer than that of the hearing samples to ensure that in the correlation, time shifts between the hearing samples and the program samples can be compensated by a displacement in time of the hearing samples with respect to the program samples.
5. The method of claim 4 , wherein the comparison of the hearing samples with the program samples is effected in two passes, wherein a first pass comprises comparing a respective hearing sample to all program samples using said first correlation, the calculation of which uses coarse graduation of the time shift, and wherein a second pass comprises using a second, more rugged correlation which provides a finer graduation of the time shift.
6. The method of claim 5 , wherein the second correlation is used in the case where the first correlation yields a correlation value c t above a predetermined value for a time shift.
7. The method of claim 5 , wherein the second correlation provides a resolution of the time shift which is at least twice as high as that obtained with the first correlation.
8. The method of claim 5 , wherein said second correlation is chosen such that great deviations between the hearing and the program sample have a smaller influence upon the correlation coefficients than the first correlation.
9. The method of claim 5 , wherein said second correlation is effected according to the formula
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N: number of hearing sample values used in the correlation,
t: time shift between the hearing and the program sample,
s i : hearing sample value at the time i,
m i-t : program sample value at the time i−t, and
a: scaling factor which takes account of the damping of the program signal with respect to the hearing sample;
r t : correlation value for the shift t, 0 (optimal correlation)<r t <1 (no correlation), a being determined in such a manner that r t assumes a minimal value.
10. The method of claim 5 , wherein the first correlation is a standard correlation according to the formula
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N: number of values of the hearing sample which are used in the correlation,
t: time shift
s i : hearing sample value at the time i,
m i-t : program sample value at the time i−t,
c t : correlation value for the time shift t: −1≦c t ≦1.
11. The method of claim 1 , wherein the hearing sample values are integer binary numbers having a fixed number of binary digits (bits) from 3 to 16.
12. The method of claim 11 , where the number of digits is from 4 to 8.
13. A computer program which causes a processor of a computer to execute the computer program, whereby the processor performs a method of evaluating recorded hearing samples of ambient noise recorded by at least one first device in at least one first location where programs to be monitored are received, the hearing samples being obtained by a method comprising recording samples of an ambient noise using a sound transducer, the computer program being stored in a computer storage readable medium of the computer and being accessed by the processor of the computer to execute the computer program, whereby the processor performs the method of evaluating the recorded hearing samples, the method of evaluating the recorded hearing samples comprising
recording, by at least one second device in at least one second location where the programs to be monitored are broadcast, a plurality of samples of the programs to be monitored wherein each of the samples of programs to be monitored has a greater duration than a corresponding one of the recorded hearing samples, and
calculating a first correlation for comparing the hearing samples with the program samples in order to find a match, a match occurring if a program sample is considered to be contained in a hearing sample,
each of the hearing samples being taken during a respective first period of time completely included in a respective second period of time during which a corresponding one of the program samples is taken.
14. A magnetic, optical or magneto-optical data carrier with the computer program of claim 13 .
15. Method for evaluating hearing samples recorded by at least one first device in at least one first location where programs to be monitored are received, the hearing samples being obtained by a method comprising recording samples of an ambient noise using a sound transducer, the method for evaluating hearing samples comprising
recording, by at least one second device in at least one second location where broadcast signals of the programs to be monitored can be recorded, a plurality of samples of the broadcast signals of the programs to be monitored wherein each of the samples of programs to be monitored has a greater duration than a corresponding one of the recorded hearing samples, and
calculating a first correlation for comparing the hearing samples with the program samples in order to find a match, a match occurring if a program sample is considered to be contained in a hearing sample,
each of the hearing samples being taken during a respective first period of time completely included in a respective second period of time during which a corresponding one of the program samples is taken.
16. A computer program which causes a processor of a computer to execute the computer program, whereby the processor performs a method of evaluating recorded hearing samples of ambient noise recorded by at least one first device in at least one first location where programs to be monitored are received, the hearing samples being obtained by a method comprising recording samples of an ambient noise using a sound transducer, the computer program being stored in a computer storage readable medium of the computer and being accessed by the processor of the computer to execute the computer program, whereby the processor performs the method of evaluating the recorded hearing samples, the method of evaluating the recorded hearing samples comprising
recording, by at least one second device in at least one second location where broadcast signals of the programs to be monitored can be recorded, a plurality of samples of the broadcast signals of the programs to be monitored wherein each of the samples of programs to be monitored has a greater duration than a corresponding one of the recorded hearing samples, and
calculating a first correlation for comparing the hearing samples with the program samples in order to find a match, a match occurring if a program sample is considered to be contained in a hearing sample,
each of the hearing samples being taken during a respective first period of time completely included in a respective second period of time during which a corresponding one of the program samples is taken.
17. Method for evaluating hearing samples of ambient noise recorded by at least one first device in at least one first location where programs to be monitored are received, the hearing samples being obtained by a method comprising recording samples of an ambient noise using a sound transducer, the method for evaluating hearing samples comprising
recording, by at least one second device in at least one second location where the programs to be monitored are broadcast, a plurality of samples of the programs to be monitored wherein each of the samples of programs to be monitored has a greater duration than a corresponding one of the recorded hearing samples, and
calculating a first correlation for comparing the hearing samples with the program samples in order to find a match, a match occurring if a program sample is considered to be contained in a hearing sample,
each of the hearing samples being taken during a respective first period of time completely included in a respective second period of time during which a corresponding one of the program samples is taken.